Waveguide Resonators — Lesson 3

This lesson covers the concept of transmission line resonators, focusing on waveguide resonators. It explains how at higher microwave frequencies, transmission line resonators have a relatively low value of Q. The lesson also discusses how waveguide resonators are usually short-circuited at both ends, forming a cavity where electrical and magnetic energy is stored. The lesson further delves into the resonant frequencies of rectangular cavities, the unloaded Q of the cavity, and the coupling to cavity resonator. It also provides a detailed explanation of the resonant frequencies for TE mn or TM mn mode. The lesson concludes with a discussion on the Q factor for cylindrical cavities and their application in frequency meters.

Video Highlights

00:28 - Introduction to Waveguide Resonators
02:37 - Determining the Resonant Frequencies of Rectangular Cavity
08:20 - Calculation of Unloaded Q of TE10l Mode
16:25 - Discussion on Power Loss on Conducting Walls
22:36 - Introduction to Circular Waveguide Cavity Resonator
28:03 - Use of Cylindrical Cavity Operating at TE 011 Mode in Frequency Meters

Key Takeaways

- Waveguide resonators are usually short-circuited at both ends, forming a cavity where electrical and magnetic energy is stored.
- The resonant frequencies of rectangular cavities can be determined assuming that the cavity walls are lossless.
- The coupling to cavity resonator can be done using a small aperture, a probe, or a loop.
- The Q factor for cylindrical cavities can be determined in the same manner as in rectangular cavities.
- Cylindrical cavities operating at TE 011 mode are often used in frequency meters due to their higher values of Q.